Method and apparatus for adjusting clutch release levers



Nov. 3, 1953 R. c. ZEIDLER 2,657,732

1 METHOD AND APPARATUS FOR ADJUSTING CLUTCH RELEASE LEVERS Filed March 24, 2 Sheets-Sheet 1 fnveni inf fieinf co e7 Nov. 3, 1953 I R. c. ZEIDLER 2,657,732

METHOD AND APPARATUS F'oR' ADJUSTING CLUTCH RELEASE LEVERS Filed March 24, 1948 v 2 Sheets-Sheet 2 s 1 l I I I x N n g q I I g? Q/ 1 J i a Q w I Q V K I l [III/4],

fnueni or'" fiezlnkalcz ZezLcZZer Patented Nov. 3, 1953 OFFICE "am'rnon "ANDY APPARATUS-FOR ADJUSTING NQIEULCIIQHIRELEASEILEVERS' lteinhold 1 C.,; Z eidler, Detroit, -Mich., assignor to .--'Borg -vWa1'-ner -Corporation,. Chicago n! a corff porationoijlllil iois @Pm fim 9 8,-Seri a1 No. 16;s31

m .1 c 'lhisinvention-relates toimprovements in friction type clutches such; as are used: in :automotive vehicles, and more particular-ly;isgidirected =toapparatusjfor and a -inethod of predeterminadjusting-or setting the operative position of-the control or release levers of such clutches. "I"he long:orinner ends of such levers are usually contacted;by,f'oiziconnected to; asi cclla'r or release-bearing?the-latteriofi which mayzb'elac- 1 tuated bywautomatic means or by- 'afclutchz-pedal; I

I through: appropriate linkagie .mechanism; to cause "-thelevers to 'shifti iii-pressure. plate ire'lati-ve-iito aflywheellnstru'cture to clamp or frictionallyzengage a clutch disc (carrying. irictiomfaci-ngsbirbe- *{tween 'saidiplate=and the fiywheelaesuch anaar- I-rangement is; commoriin .the.prior.art,,;and:;the inventijonherein di'sclosed is applicablerithereto. ends of the 'lev'er's.- whichl areeengageable with the release bearing, above: ref erred mo, are generally identified as the leverutipss-andin all ordinary elutclis it is' necessar-y toipred'etermine, 5 within practical-"operating (limits; the positions of such tips for engagement iloyr=the relea'se. bearing. l The careful positioning of these -'1ever. .'tips is desirable in order-that the'outer, planarisuriaoe v of'the pressure gplateiwillabe maintainedinlai plane parallel to the inner planarfface': oiZthe flywheel to. provide a well lbalanced: assembly, andiwherein the clutch disc may: be:more-efl'icientlyi controlled T and'excessive -wear:arid deterioration-Iprevented.

1Heretofore various means,-

-including;,screws, bolts, and- .shimsl have be'en::employed,. to ;make the clutch leversiadju'stable: "Such adjustments I 'are gene r ally made on an assembly. pfix ture son 1 "which I the individual :.components'; of: lathe: clutch are assembled, afteriiwhich the. clutch is compressed to '-i'ts -operatin'g .positionltat lWhlChijthB sj fg are -hadjustedflfand aeach' checkedwjor heigh't at its: tipawith a: micrometeredial indicater or other convenient means. 2-*-'-1 he- :levers adjusted :for each assembly :and ar'e-prefmust be erably iadjusted so that" thercontactinggfaces; or points; of: :thextips: are;:'-.d PO S di-. 1: a; pla fiaia th ough;as a:practical matteryitis notinons filer d objectionable ifJthey-a're eheld'iwithinanaaxialflis tame oi -.010- to 1030" of:ari:inchaiE-Ieretoiore,warious means'have beeniusedz to: lock OESIGtfiiIlTl-Mle adjustable means so that the xpOSi-fiOn'EOfi-IIIIB i.1' s will: techgng' during operations .Gen-

'erany afte'r the initial adiustmnti andi Such lock-i 2 ing, the levers are again tested for height in an ;;efi ortto :make certain that the manufacturing operations 7 have; not disturbed the adjustment and to take such steps as are possibleto make 07 sure thatcontinued operation of, the levers will not release;or disturb -the adjustment. Suchadjustrnents are time consumingand difficult and when parts are displaced or outof order, the ,clutch assembly; is out of alignment and balance 0 ;,with the result that the clutch assembly will not operate satisfactorily. Clutch operating levers areusually constructed oisteel-or; malleable iron having known characteristics. 'I'heyVInay be; stampings, forgings or castings, andtheir ratios usually lie between 3 to 1 and?v to 1. S ince only a small space isavailable, itgenerallyresults in-the use of levers in which the maximum bending stress is concentrated at or adjacent to the fulcrum provided by the cover member.

By utilizing this fact and the physical characn; teristics of the metal used-in the levers I have ,accomplis'hed one of theimportant objects of this invention, which is to design and construct the levers in a manner whereby the position. of the leventips can bepredetermined by bendingor distorting the; levers somewhat inexcess of their elastic propertiessothat they will take a decided set, closely enough. in plane so the operation of 3 thevclutch is notimpaired.

One ofkthe important objects of the subject inyention is lac-simplify the idesig'n'and reduce costs v .in manufacturel'and.assembly. In this connectiori, .it is,an ,object to'ielirninate all of the extra parts oruelements usually. required to make the levers; adjustable.

Another object ofthe invention is to reduce to a minimum'the time, efiort, and skill customarily he required, to adjustset, or. predetermine the oper- 40 ative positionsofisuch levers.

Apartieular object of the invention is to provide a unique, method w he reby the position of the leve'rc'tips, engageable with the release bearing are allimadeto lie'substantially in a single plane by distorting -or h bend ing, the levers to appoint l where they will ,take aj-set, such point generally leeingmreached when therdistortion exceeds the ia stio limit of,the::;material oflwhich the levers are made. 7 A -n additionalobject of the invention is to deact n'i'iaa 3 sign and construct each of the levers with an intermediate weakened portion at or adjacent to its normal critical section so that under a bending load higher than encountered in normal operation the stress at such weakened portion or section will exceed the elastic limit of the material to cause a substantially permanent deformation of the lever. Thus, the levers may all be bent to a predetermined dimension causing simultaneous permanent deformation at such portions, the strength of such portions being sufficient to carry all normal operating loads and at the same time avoid taking any additional permanent set. It is to be understood that the term weakened may apply either to a lever of substantially uniform cross-section having an opening therein to weaken the structure at an appropriate location or one provided with an intermediate restricted portion, or some other desirable arrangement. It Will therefor be manifest that the weakened portions can all be made identical and held to relatively close limits so that the sets resulting from the distortion will be uniform. The levers may be constructed from any suitable material for the purpose, but that proven most desirable is low carbon steel of S. A. E. 1010 or 1020 analysis subjected to a cyanide case hardening treatment, as it ha great ductility and a high elongation factor.

Many other objects and advantages of the invention will become apparent after considering the description hereinafter set forth in conjunction with the drawings annexed hereto.

In the drawings, wherein identical parts of the structure are identified by the same reference characters:

Fig. 1 is an end view in elevation of a cover and pressure plate assembly illustrative of a device to which the present invention is directed;

Fig. 2 is an enlarged transverse sectional view of such assembly taken substantially on line 2-2 of Fig. 1 and looking in the direction of the arrows;

Fig. 3 is a transverse sectional View of a lever taken on line 3-3 of Fig. 4; and

Fig. 4 illustrates a fixture upon which the cover plate assembly is mounted, including means for simultaneously setting the position of the lever tips.

The preferred assembly embodying the improved principles of design, construction, and method constituting the invention includes a cover or housing I, a pressure plate 2 disposed in the cover, a clutch friction disc subassembly 3, and a plurality of levers 4 which are operatively connected to the pressure plate and fulcrumed on the cover at bearing points 5 in a -manner whereby a release bearing 6, operable by a clutch pedal, will actuate the levers to control the movement of the plate and disc with respect to the planar face i of a flywheel 8 to transmit power from the flywheel to a transmission shaft or the like, as desired.

The friction disc subassembly 3 may be of conventional design and as shown comprises a metal disc 9 having fixedly secured to its outer marginal zone inner and outer friction elements I and II which, as clearly illustrated, are located between and operatively engageable with the planar surface 1 of the flywheel and a planar face l2 of the pressure plate. The disc 9 is mounted on a hub l3 which may have an integrally formed radial flange M. The hub, as shown, is spline connected as at to a driven shaft IS.

A vibration dampening structure, corresponding for example, to the one described in United States Letters Patent No. 2,042,570, is associated with the disc 9 and the flange I4 of the present structure to provide a flexible driving connection between them. For this purpose the disc and hub may be connected by an arrangement in the form of an annulus of coiled springs I! located in aligned openings i8, I9 and in the disc, flange, and a washer 2|. The disc and washer are preferably secured together for simultaneous movement by means of long spacers 22, having reduced ends which extend through holes provided therefor in these members and are upset as shown in Fig. 2. The spaces also include enlarged cylindrical portions 23, which extend through notches 24 interrupting the periphery of the radial flange M and serve to connect and maintain the disc and washer in spaced parallel relationship, the size of the notches and cylindrical portions of the rivets being such that relative movement may take place between the disc and washer as a unit and the hub. This relative movement may be controlled and dampened in some measure by friction materials 25 disposed between the hub flange, disc and washer. Driving forces are transmitted from the disc to the hub and vice versa through the conventional coil springs or dampeners ll.

It will be observed that the aligned openings in the disc and washer may have radial dimensions less than the diameter of the springs so that the springs will be held in proper operative positions.

The cover may be constructed as desired, but as herein illustrated is preferably fashioned to impart stability and made generally triangular in shape. It includes, among other things, an inset fiat wall portion 26 provided with a relatively large central round opening 21 for the release bearing and shaft [6 carrying the bearing. The cover as shown also includes at least three generally axial wall portions 28, outwardly extending inclined wall portions 29, and an outwardly extending radial border flange 30 joined to the inclined walls. The border flange 30 is continuous and formed to provide a pair of apertured flat land portions 3| adjacent each corner extremity of the cover, which lands are normally disposed in a single plane and firmly anchored against the planar face I of the flywheel by any convenient means, such as screws 32 (Fig. 2). These lands also serve an additional purpose which will be referred to later.

Each of the inclined wall portions 29 is provided with a rectangular axial clearance opening 33 through which three rearwardly extending lugs 34 integral with the pressure plate project. The extremities of the lugs are bifurcated and provide rigid supports for the semicentrifugal levers, which are pivotally mounted in the bifurcations by pivots 35. The ends of the lugs are preferably made flat as indicated at 36 and disposed in a single plane for a purpose to be described subsequently. The levers are constructed to project through square radial openings 31 provided in the axial wall portions 28 so that the inner contact surface or points 38 on the tips or ends 39 of the levers are located in the cover for engagement with the planar bearing surface 40 of the release bearing. Attention is directed to the fact that the forward marginal edge of each opening 31 constitutes one of the fulcrum bearing points 5 above referred to.

The pressure plate 2 includes a ring or annular portion 4| having the planar face 12 which 4, which is the adjusted normal operating position.

In order to insure uniform results, it has proven desirable to hold the levers to the full line adjusted position, just referred to, for a period of approximately 3 seconds, whereby to allow sufficient time for the material of the lever at the critical point to exceed positively the elastic limit and set.

Obviously, the assembly fixture could have the air clamps and ram Operated by a Single valve so that the first movement of the valve handle would cause the cover border flange and pressure plate lugs to be held while additional movement would cause the ram to do its work. Also, an automatic timer could be advantageously associated with the valve structure.

In running deflection and set computations on levers of the type illustrated, it was discovered that after passing through the yield point of the material the stress was proportional to the .strain applied to the lever through a considerable range; that by plotting the corresponding permanent set against the deflection of the lever, the permanent set and deflection was proportional; and that the set when once made per- .manent would hold until the ultimate strength of the material is reached. These results, however, will not hold true at any point below the yield point, because according to Hookes law the proportionality of stress to strain holds true only up to the proportional elastic limit. It will therefore be manifest that in order to set the "practical limits, by one controlled bending operation.

If a series of such levers being out of plane are deflected to a given dimension, the out of plane, after the deflecting means has been removed, would be considerably less than originally. This is because the lever highest from the supporting face 54 of the fixture will take a greater permanent set due to having been deflected more than the lever that was lowest and any lever in between will take a permanent set somewhere between the highest and lowest lever. It has also been discovered that with a given design of lever :and type of material, a deflection of between .080 and .150 of an inch gave the best correction for out of plane. As a corrective deflection drops to less than .080 of an inch, the reaction of the lever to taking a permanent set usually becomes unreliable.

Production tolerances, where a series of levers are to be set at one time, will depend on what permissible final out of plane is allowable. If, for example, the final result is to be within .005 of an inch, the maximum out of plane originally should not be over .030 of an inch. If a greater tolerance on the final out of plane is allowable, production tolerances on the manufactured parts can be varied accordingly.

As stated above, the object of the notch 52 is to deliberately weaken the lever adjacent the bearing portion 41 so that when the lever is stressed beyond its elastic limit, to modify its molecular characteristics, a permanent set or deformation will take place only at this localized section. This arrangement is most advantageous because the cross-sectional area can be held to closer limits or dimensions at a localized point than throughout the length of the lever, and theresulting uniformity of the set will be closer. The levers described are preferably adapted for use in 8 and 8% inch size clutches and with the proper spring load necessary to transmit the torque of engines with which they may be used, the load on the lever tips will be approximately pounds per lever. It has been proved that once the lever has been permanently set by applying a load or force of 200 pounds or more, no additional set takes place if a load of only 100 pounds is applied.

While I have illustrated the preferred application of the invention it is to be understood that many other modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of the construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

I claim:

1. A method of setting the position of the inner operating ends of the levers in a clutch assembly, which consists in placing the assembly on a fixture to hold the levers against movement relative to the other parts of the assembly, and the other parts of the assembly against relative movement to maintain the levers and other parts of the assembly in fixed relation and then applying bending stress in an axial direction to the ends of the separate levers to simultaneously impart a permanent set to the levers with their ends all disposed in a common plane at substantially right angles to the longitudinal axis of the P assembly.

2. The method of positioning in predetermined relationship the power-receiving radially inner ends of the operating levers of a clutch assembly which includes a pressure member in a cover and the radially outer regions of the levers fulcrum on the cover and are attached to the pressure member, said method comprising the steps of changing the original shape of the levers by applying pressure to the separate levers axially of the assembly to simultaneously distort them to a permanent condition at locations between the fulcrums and the inner extremities of the levers to thereby set the power-receiving ends of the levers in a substantially common plane.

3. A method of positioning the ends of a plurality of levers associated with a pressure plate and cover of a clutch in a predetermined relationship which consists in assembling the levers wit a plate and cover, holding the pressure plate and levers against movement relative to the cover, and then applying sumcient pressure to simultaneously bend the levers in a direction axially of the pressure plate and cover to impart a permanent set to the levers so that their ends will remain in a substantially single plane when the pressure is released, the pressure applied to bend the levers being substantially greater than the pressure applied during operation of said levers to move the pressure plate during normal operation of the clutch.

4. A method of positioning in predetermined relationship the radially inner ends of a plurality of levers in a clutch which includes a pressure member in a cover and the radially outer regions of the levers fulcrum on the cover and are attached to the pressure member, said method comprising weakening a portion of each of the levers, holding the pressure member and cover against movement relative to each other, bending the levers simultaneously at their weakened portions to stress the weakened portions beyond the elastic limit of the material thereof to set the material and rectify possible error due to manufacturing variations and thereby position the levers in a predetermined manner relative to each other.

5. The method of positioning in predetermined relationship the radially inner extremities of the operating levers of a clutch assembly including two drive members connected to each other for conjoint rotation and relative axial movement and in which the levers are pivotally attached to one member and fulcrumed on the other member, said method comprising the steps of holding the drive members against relative axial movement, and applying forces to the radially inner extremities of the separate levers to simultaneously bend regions of said levers beyond their elastic limits with sufiicient pressure to impart a permanent set to the l vers and thereby position the radially inner extremities of the levers in a predetermined relationship with respect to each other.

REINHEOLD C. ZEIDLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 279,618 Wells June 19, 1883 1,568,583 Anderson Jan. 5, 1926 1,634,913 Rainsford July 5, 1927 1,925,804 Hiering Sept. 5, 1933 1,927,643 Hughes Sept. 19, 1933 1,962,797 Wemp June 12, 1934 2,195,354 Bateman Mar. 26, 1940 2,219,595 Lang Oct. 29, 1940 2,417,035 Zeidler Mar. 4, 1947 FOREIGN PATENTS Number Country Date 194,363 Great Britain Mar. 5, 1923 

